May 2019
Spotlight Summary by Dae Wook Kim
System design of a single-shot reconfigurable null test using a spatial light modulator for freeform metrology
Freeform optics allow higher degrees of freedom in optical design-space, enabling greatly enhanced imaging performance within compact and ergonomic form factors such as AR (Augmented Reality) glasses and wide field-of-view space telescope applications. If you have a novel freeform design solution, the next challenge is the manufacturing of the optical system. While there are various computerized freeform optics fabrication technologies, freeform metrology solutions have been largely limited by their adaptability to various freeform optics surface shapes and highly aspheric wavefronts. For a customized freeform optical testing, a CGH (Computer Generated Hologram)-based null test can be configured to test a few hundreds of microns of freeform sag departure at the price of significant expense and lead time for the custom CGH manufacturing and verification.
The authors present a highly flexible and adaptable nulling solution utilizing a SLM (Spatial Light Modulator), which can manipulate the test beam wavefront in order to match the required nulling phase for a large range of freeform optics. Compared to other adaptable approaches such as a DM (Deformable Mirror)-based solution [L. Huang, H. Choi, W. Zhao, L. R. Graves, and D. W. Kim, "Adaptive interferometric null testing for unknown freeform optics metrology," Opt. Lett. 41(23), 5539-5542 (2016)], the reported adaptive interferometric test using a high-definition phase-only SLM measures a freeform surface with a larger dynamic range, covering up to a sag departure of 150 μm from its base-sphere. In summary, this letter nicely presents a smart and versatile interferometric nulling technology with a programmable phase component for single-shot interferometric measurement of freeform optics.
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The authors present a highly flexible and adaptable nulling solution utilizing a SLM (Spatial Light Modulator), which can manipulate the test beam wavefront in order to match the required nulling phase for a large range of freeform optics. Compared to other adaptable approaches such as a DM (Deformable Mirror)-based solution [L. Huang, H. Choi, W. Zhao, L. R. Graves, and D. W. Kim, "Adaptive interferometric null testing for unknown freeform optics metrology," Opt. Lett. 41(23), 5539-5542 (2016)], the reported adaptive interferometric test using a high-definition phase-only SLM measures a freeform surface with a larger dynamic range, covering up to a sag departure of 150 μm from its base-sphere. In summary, this letter nicely presents a smart and versatile interferometric nulling technology with a programmable phase component for single-shot interferometric measurement of freeform optics.
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Article Information
System design of a single-shot reconfigurable null test using a spatial light modulator for freeform metrology
Romita Chaudhuri, Jonathan Papa, and Jannick P. Rolland
Opt. Lett. 44(8) 2000-2003 (2019) View: Abstract | HTML | PDF